Of course, the notion of a condensed workweek is nothing new. Fans of the four-day week have been espousing its benefits from a productivity and cost-cutting perspective since the 1970s. Indeed, in 1974, when the British government introduced a three-day workweek following an energy shortage, a national survey reported a 5 percent increase in productivity levels.

However, with job disruption on the up and employees demanding greater flexibility at work, its scope is growing. A lifestyle that was once limited to a select few now "fits with more industries and jobs than you might imagine," Jim Link, chief human resources officer (North America) at global recruitment agency Randstad, told CNBC Make It.

"Savvy employers are catching on to the fact that employees are increasingly demanding better work-life balance and the opportunity to get work done at non-traditional places and times," said Link. "The four-day workweek is a perfect example of that."

Lindsay Grenawalt is head of people at Cockroach Labs, a New York-based computer software company that has been running its version of the four-day week – "Free Fridays" – since it was launched by three former Google employees in 2015. Designed neither strictly for working nor strictly for downtime, Cockroach Labs' "Free Fridays" are intended as an opportunity for staff to "take back control," with many using them for study, long-term projects or family time.

As an HR manager, Grenawalt noted that she was "open-mouthed" when the founders first presented her with the idea. But, having seen it work in practice in her two years at the company, she said it has challenged her to "think outside the box" about new ways to stay competitive and motivate employees.

"It's very contrary to what American culture is, but I think if we're going to hold onto talent we have to get creative about how you're going to hire and retain talent," she said. According to the Bureau of Labor Statistics, the average American works 44 hours per week, or 8.8 hours per day.

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How viable is it?

While there's no cut and dried rule for how a four-day week would work, some suggest the most sensible option is to add an extra hour or two to each of the other workdays to compensate for lost time.

According to FlexJobs' Rachel Jay, a career writer, that could be a "boon" for workers' productivity, providing them with "longer stretches of uninterrupted time to work."

However, Adam Edwards, business director (Singapore) of global recruitment firm Hays, noted that "pressure on individuals to achieve the same output in four days as they have done previously in five could have a negative impact on stress levels."

There are concerns about other negative implications, too. For instance, some have suggested a shorter workweek could hamper wages and potentially cause friction among professions that are less able to adapt, such as many manufacturing and medical roles.

To manage those issues, Link said employers would have to think carefully about how they structure the work schedule and communicate that to staff.

"The challenge is making sure productivity doesn't slip and that employees remain accountable to their bosses, customers, etc.," said Link.

"As with any flexible work arrangement, misunderstandings are best avoided through regular, clear communication. Being upfront about expectations for employees with a four-day workweek — for example, is someone still 'on call' to respond to customer inquiries? — goes a long way toward keeping everything running smoothly," he added.

Making a 4-day week work

For those looking to give the four-day workweek a try, Grenawalt gave her three-step guide to making it work.

1)Focus on hiring

It might sound obvious, but the first step to having productive staff is to make sure they actually want to be there in the first place, said Grenawalt.

Cockroach Labs works especially hard at the recruitment stage to test that commitment, using techniques such as exercise-based tasks to make sure candidates can demonstrate their abilities as well as just talk about them.

"If we didn't invest as heavily as we do in the hiring process, I think there could be difficulties," Grenawalt noted.

2) Consolidate meetings

Secondly, it's important to create a work environment that's conducive to a shorter week. For Cockroach Labs, that means restricting all team meetings to Tuesdays so Fridays can be left undisturbed.

Grenawalt said managers are trained to respect those restrictions, so that group work is only requested on Fridays under special circumstances.

3) Cut out distractions

Finally, make it as easy as possible for staff to get their work done by removing distractions.

To help with that, Cockroach Labs provides staff with noise-cancelling headphones and has installed red and green LED lights at each desk so employees can indicate whether or not they're happy to be disturbed.